1. Field of the Invention
The present invention relates to an article identifying system which is used to manage tools of a machine tool, or parts or products in a factory or to identify articles in a distribution or delivery system or the like.
2. Description of the Prior Art
Hitherto, in order to automate the management of tools of a machine tool, identification of parts or products in assembly and transport lines in a factory, or the like, it is necessary to use a system to identify and manage various kinds of articles such as tools, parts, products, and the like. As such a conventional managing system, there has been known a system in which labels having bar codes or the like are adhered to objects to be detected, thereby identifying and managing the objects, or a system in which a group of magnets representing data by a binary value is attached to an object to be identified and the polarities of predetermined magnets are inverted from the outside, thereby giving data. However, these systems have problems such that it is troublesome to rewrite data, the reliability of data is low, and an amount of information which can be held is little.
To eliminate these problems, there has been also proposed an article identifying system in which a memory is provided for an object to be identified, necessary information is previously stored in the memory by the data transmission of a contact type or base band type, and this information is read out as necessary.
However, such a conventional identifying system has drawbacks such that a backup battery is needed to keep the data in the memory, it is troublesome for management, and shock resistance and vibration resistance are low.
Although a contact type system or a contactless type system is considered as a data transmission system, the contact type system has problems such that the positioning needs to be accurately performed, defective contacts easily occur in the contact portions, and data cannot be certainly written.
On the other hand, the contactless type system includes a conventional base band system in which electromagnetic waves or the like are intermitted on the basis of a digital signal to be transmitted, thereby giving the transmission signal and electric power to a memory unit which is attached to an article. However, this system has a problem such that the reliability is low. In addition, according to the data transmission by the base band system, there are also drawbacks such that a supplying efficiency of an electric power to the memory is low and the memory itself needs a power source because the frequency is low and the electromagnetic waves are intermitted. Further, there is also a problem such that when metal material or the like approaches this system, the output level of a receiving circuit of electromagnetic waves fluctuates and the reliability of data is low.